Exporting DAGMC Models
DAGMC (Direct Accelerated Geometry Monte Carlo) is an open-source toolkit for performing Monte Carlo radiation-transport simulations directly on CAD-based geometry. CUBIT can export a model to the MOAB-compatible .h5m file that DAGMC and the transport codes built on it (such as OpenMC and MCNP) consume.
The command used to export a DAGMC model is:
Export DAGMC '<filename>' [Overwrite]
Use the overwrite keyword to replace an existing file. The exporter writes the faceted (triangulated) surface mesh together with the geometric topology — vertices, curves, surfaces, and volumes — and the tags, surface senses, and group information that DAGMC requires, all in the HDF5-based .h5m format. Block names are recorded in the file decorated with the assigned material and its first few property values (for example mat:steel/ela:2.00e+11/poi:0.30); long names are truncated to the 31-character tag limit, with a warning when that happens.
Preparing a Model for DAGMC Export
A DAGMC model is a watertight surface mesh in which adjacent volumes share surfaces, so that particles can be tracked from one volume into the next. The typical preparation steps are:
- Imprint and merge the geometry so that
neighboring volumes share common surfaces:
imprint body all
merge body all - Assign a material to every volume, including void regions, by placing the volumes in blocks and assigning a material to each block. The material name travels with the block into the exported file.
- Mesh the surfaces. Surfaces are meshed with the TriMesh scheme. For transport models the Trimesher Coarse setting is often used to produce a fast, sparse surface mesh that is coarse over flat regions and finer over curved regions.
Note: The command export cf_dagmc is a deprecated alias for export dagmc and will be removed in a future release. (Older tutorials may still refer to export cf_dagmc.)